Contents

States of Consciousness

States of Consciousness

Altered States

Review Questions

Consciousness

Consciousness is the awareness people have of themselves and
the environment around them.

The level and state of consciousness vary. Different states of
consciousness are associated with different brain wave patterns. Brain
waves are tracings that show the kind of electrical activity going on
in the brain. Scientists use an electroencephalograph, or EEG, to
record these waves.

The main types of brain waves are alpha, beta, theta, and delta.

Sleep

Types of biological rhythms include circadian, infradian, and ultradian rhythms.

Endogenous biological rhythms originate from inside the body
rather than from the outside environment.

Biological clocks in the body regulate the sense of time.

The suprachiasmatic nucleus regulates circadian rhythms of
sleep.

Different theories suggest that people sleep to conserve energy, stay safe
from predators, or restore body tissues depleted during the day.

Researchers use EEGs, EMGs, EOGs,
and EKGs to record sleep patterns.

There are five stages of sleep. At each stage, different types of brain
waves function, and heart rate, breathing, and temperature vary.

During REM sleep, heart rate and breathing become irregular,
eyes move rapidly, and muscles relax. Dreams are most vivid during REM sleep.

Sleep patterns change as people age, with most people needing less sleep
as they get older.

Sleep disorders include insomnia, narcolepsy,
and sleep apnea.

Dreams

Sigmund Freud believed that dreams allow people to express
unconscious wishes. He said the manifest content of dreams, or the
dream’s plot, symbolizes the latent content, or hidden meaning.

The activation-synthesis theory proposes that neurons in the
brain randomly activate during REM sleep. Dreams arise when the cortex tries to
make sense of these impulses.

Altered States

Altered states are induced states of consciousness and
include hypnotic states, meditative states, and drug-induced states.

In hypnosis, a hypnotist makes suggestions to a person. One
theory states that people in hypnosis divide their consciousness into two parts.
Other theories say that people merely play a role when hypnotized.

Meditation is the practice of focusing attention.

Psychoactive drugs are usually used for recreational rather
than medical purposes, though some have legitimate medical uses. These drugs
change sensory experience, perception, mood, thinking, and behavior.